Expandable medical implants are often useful at least because the implants may be introduced into a surgical site with a reduced profile that facilitates reduced disruption of surrounding tissues. Expandable medical implants may be useful in at least some spinal fusion procedures and in at least some vertebral body replacement procedures. Spinal fusion procedures are often effective to restore proper vertebral spacing and relieve pressure on nerves and consequent pain. Also, it is sometimes necessary to remove one or more vertebrae, or a portion of the vertebrae, from the human spine in response to various pathologies. For example, one or more of the vertebrae may become damaged as a result of tumor growth, or may become damaged by a traumatic or other event. Removal, or excision, of a vertebra may be referred to as a vertebrectomy. Excision of a generally anterior portion, or vertebral body, of the vertebra may be referred to as a corpectomy. An implant is usually placed between the remaining vertebrae to provide structural support for the spine as a part of a corpectomy or vertebrectomy. This may generally be referred to as vertebral body replacement.
Many prior art devices have deployed expandable medical implants with the aid of relatively large or complex insertion, expansion, distraction, and retraction instruments. Some devices require a significant incision and retraction of tissue to enable controlled expansion of the implant. A smaller incision may be particularly useful with a posterior approach to the spine. To effectively make a posterior approach, an implant may be placed through a window created between a nerve root, the spinal cord, and an extent of an excised vertebra. The nerve root may be mobilized to increase the size of the window slightly, but excess movement may risk damage to the nerve root. Therefore, for a posterior approach, an initially small expandable implant may have particular utility. A posterior approach may be preferred for patients with circumferential tumors or for patients more susceptible to the risks associated with a more extensive anterior approach. Similarly, initially small implants enabling minimal tissue disruption may be useful from any surgical approach to reduce trauma to surrounding tissues and to enhance patient recovery. Likewise, a deployment mechanism that does not require tissue disruption beyond the disruption required to introduce an implant is advantageous.
Connections between bones and implants may also be useful in replacing bones or portions of joints or appendages such as the legs and arms, or other bones. Examples include, but are not limited to, a femur, tibia, fibula, humerus, radius, ulna, phalanges, clavicle, and any of the ribs. Use of the mechanisms described and claimed herein are equally applicable to treatment or repair of such bones or appendages.